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       r3.gwflow   -  Calculates  numerically  transient,  confined  groundwater  flow  in  three


       raster3d, voxel


       r3.gwflow help
       r3.gwflow [-ms] phead=string status=string hc_x=string hc_y=string hc_z=string  [q=string]
       s=string    [r=string]    output=string    [velocity=string]    dt=float   [maxit=integer]
       [error=float]   [solver=name]   [relax=float]   [--overwrite]  [--verbose]  [--quiet]

           Use 3D raster mask (if exists) with input maps

           Use a sparse linear equation system, only available with iterative solvers

           Allow output files to overwrite existing files

           Verbose module output

           Quiet module output

           Input 3D raster map with initial piezometric heads in [m]

           The status for each cell, = 0 - inactive, 1 - active, 2 - dirichlet

           The x-part of the hydraulic conductivity tensor in [m/s]

           The y-part of the hydraulic conductivity tensor in [m/s]

           The z-part of the hydraulic conductivity tensor in [m/s]

           Sources and sinks in [m^3/s]

           Specific yield in 1/m

           Recharge raster map in m^3/s

           The piezometric head result of the numerical calculation will be written to this map

           Calculate the groundwater distance velocity vector field
           and write the x, y, and z components to maps named name_[xyz].Name is basename for the
           new 3D raster maps.

           The calculation time in seconds
           Default: 86400

           Maximum number of iteration used to solver the linear equation system
           Default: 100000

           Error break criteria for iterative solvers (jacobi, sor, cg or bicgstab)
           Default: 0.0000000001

           The type of solver which should solve the symmetric linear equation system
           Options: gauss,lu,cholesky,jacobi,sor,cg,bicgstab,pcg
           Default: cg

           The relaxation parameter used by the jacobi and sor solver for speedup or stabilizing
           Default: 1


       This  numerical module calculates transient, confined groundwater flow in three dimensions
       based on volume maps and the current 3D region resolution.   All  initial-  and  boundary-
       conditions must be provided as volume maps.

       The  module calculates the piezometric head and optionally the groundwater velocity field.
       The vector  components  can  be  visualized  with  ParaView  if  they  are  exported  with

       The  groundwater  flow  will always be calculated transient.  For steady state computation
       the user should set the timestep to a large  number  (billions  of  seconds)  or  set  the
       specific yield raster map to zero.


       The   groundwater   flow  calculation  is  based  on  Darcy's  law  and  a  finite  volume
       discretization. The groundwater flow partial differential equation  is  of  the  following

       (dh/dt)*S = Kxx * (d^2h/dx^2) + Kyy * (d^2h/dy^2) + Kzz * (d^2h/dz^2) + q

                     h -- the piezometric head im meters [m]

                     dt -- the time step for transient calculation in seconds [s]

                     S -- the specific yield  [1/m]

                     b -- the bottom surface of the aquifer meters [m]

                     Kxx  --  the  hydraulic conductivity tensor part in x direction in meter per
                     second [m/s]

                     Kyy -- the hydraulic conductivity tensor part in y direction  in  meter  per
                     seconds [m/s]

                     Kzz  --  the  hydraulic conductivity tensor part in z direction in meter per
                     seconds [m/s]

                     q - inner source in [1/s]

       Two different boundary conditions are implemented, the Dirichlet and  Neumann  conditions.
       By  default the calculation area is surrounded by homogeneous Neumann boundary conditions.
       The calculation and boundary status of single cells can be set with the  status  map,  the
       following cell states are supported:

                     0  ==  inactive - the cell with status 0 will not be calulated, active cells
                     will have a no flow boundary to an inactive cell

                     1 == active - this cell is used for groundwater calculation,  inner  sources
                     can be defined for those cells

                     2 == Dirichlet - cells of this type will have a fixed piezometric head value
                     which do not change over time

       The groundwater flow equation can be solved with several numerical solvers.   Additionally
       a  direct  Gauss solver and a LU solver are available. Those direct solvers only work with
       quadratic matrices, so be careful using them with large maps (maps of  size  10.000  cells
       will need more than one Gigabyte of RAM).


       This  small script creates a working groundwater flow area and data. It cannot be run in a
       lat/lon location.
       # set the region accordingly
       g.region res=25 res3=25 t=100 b=0 n=1000 s=0 w=0 e=1000 -p
       #now create the input raster maps for a confined aquifer
       r3.mapcalc "phead = if(row() == 1 && depth() == 4, 50, 40)"
       r3.mapcalc "status = if(row() == 1 && depth() == 4, 2, 1)"
       r3.mapcalc "well = if(row() == 20 && col() == 20 , -0.00025, 0)"
       r3.mapcalc "hydcond = 0.00025"
       r3.mapcalc "syield = 0.0001"
       r.mapcalc  "recharge = 0.0"
       r3.gwflow -s solver=cg phead=phead status=status hc_x=hydcond hc_y=hydcond  \
       hc_z=hydcond     q=well      s=syield      r=recharge      output=gwresult      dt=8640000
       # The data can be visualized with ParaView when exported with r3.out.vtk
       r3.out.vtk                              -p                              in=gwresult,status
       vector=gwresult_velocity_x,gwresult_velocity_y,gwresult_velocity_z out=/tmp/gwdata3d.vtk
       #now load the data into ParaView
       paraview --data=/tmp/gwdata3d.vtk


        r.gwflow, r3.out.vtk


       Sören Gebbert

       This work is based on the Diploma Thesis of Sören Gebbert available here at Technical
       University Berlin, Germany.

       Last changed: $Date: 2011-09-13 13:13:36 -0700 (Tue, 13 Sep 2011) $

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